(CNN) -- Flags flew at half-staff outside the Cherokee Nation's headquarters in Talequah, Oklahoma, on Tuesday in honor of Wilma Mankiller, the first woman to lead the Native American tribe.

Mankiller died Tuesday morning at age 64 after a battle with pancreatic cancer, Cherokee leaders announced. Her successor, Chad Smith, called Mankiller "the iconic leader of the tribe."

Mankiller served 10 years as principal chief of the Cherokee, the second-largest U.S. tribe, and became its first freely elected leader in 1987. President Clinton awarded her the Medal of Freedom, the highest U.S. civilian honor, in 1998.

She was born in Oklahoma, where most of the Cherokee had been exiled by the U.S. government in the 1830s, but moved to California with her family in the 1950s. She returned to Oklahoma in 1977 to work for the tribe's community development agency and is credited with improving health care, education and tribal governance during her administration.

"She captured what we firmly believed was true leadership," Smith said Tuesday afternoon. "She believed in our history, our culture. And she understood the position of a woman, and that is to lead her people, and she did so with grace, humility, decisiveness and with vision."

Mankiller is survived by her husband, Charlie Soap, and two daughters, Gina and Felicia, Smith said.

"We all are better people for the leadership of Wilma Mankiller," Smith said.